City of Ember(2008)

Amber city and its mayor have created a beautiful and bright world for future generations. But the main and most powerful generator of the city has a problem and all the enlarged lamps have started to turn on and off. Lena Mifleet and Don Harrow, two teenagers, decide to look for clues to unlock the town's old secret. Their goal is to help the residents of the city leave before the lights are permanently turned off...